Methyl methacrylate (MMA) is a critical raw material in the production of acrylic polymers. MMA is traditionally produced from non-sustainable, hazardous raw materials, such as acetone and hydrogen cyanide. Accordingly, there is a need in the art for MMA production methods that are sustainable and rely on non-toxic production methods.
As such a production method, methods are proposed wherein 2-hydroxyisobutyric acid and 3-hydroxyisobutyric acid to be precursors of methacrylic acids are produced from natural products such as saccharides using naturally occurring microorganisms (see Patent Literatures 1 and 2 and Non Patent Literature 1). However, these methods still rely on chemical techniques in the step for producing a methacrylic acid by dehydrating the precursor.
Additionally, there are methods proposed wherein a methacrylic acid is produced from glucose using a not naturally occurring engineered microorganism into which a plurality of enzyme genes are introduced, but these are the combination of a known enzyme reaction and a hypothetical enzyme reaction analogized therefrom and not verified (see Patent Literatures 3 to 5). Particularly, Patent Literature 5 presents examples of a wide variety of biocatalysts (hydrolase, wax ester synthase, alcohol acetyltransferase) which have typical ester-producing activity but fails to state that those biocatalysts have the synthesis activity of methacrylic acid esters.
The inventors have reported a production method of a methacrylic acid ester from methacrylyl-CoA by biocatalysts (Patent Literature 6) and a production method of a methacrylic acid ester from biomass in the presence of an alcohol by adding the action of AAT to a microorganism which has a methacrylic acid producing ability (Patent Literature 7). Additionally, the inventors have reported a method for synthesizing methacrylyl-CoA from 3-hydroxyisobutyryl-CoA using E. coli into which a dehydratase gene is introduced (Patent Literature 8).